CALIFORNIA, U.S. - Even though Google has been cautious for years about being linked to the U.S. military, the search engine giant is now said to have allowed the Pentagon to use its technology.

According to a report in Gizmodo, Google’s artificial intelligence tech is being used by the Pentagon to analyze drone footage.

After the report appeared, Google confirmed that it is allowing the Pentagon to use some of its image recognition technologies as part of a military project.

The report stated that many of the search giant's workers learned of the collaboration last week via internal emails and some were "outraged.”

Subsequently, a spokeswoman for Google said that the tie-up involved the provision of software tools to let the U.S. Department of Defense (DoD) make use of its TensorFlow machine learning code.

She said, "The technology flags images for human review, and is for non-offensive uses only. Military use of machine learning naturally raises valid concerns. We're actively discussing this important topic internally and with others as we continue to develop policies and safeguards around the development and use of our machine learning technologies."

Previously, Google pulled one of its robots from a Pentagon-organised competition because of concerns about being associated with the U.S. military.

According to the Gizmodo report, the drone initiative involved is called Project Maven - which is a scheme announced last July.

It involves the use of computer algorithms to identify objects of concern from "massive amounts of moving or still imagery."

Further, the report elaborated that the idea is to focus human efforts on sections of footage flagged for further analysis and avoid them having to wade through all the other hours of recorded material.

According to the DoD, its immediate focus would be 38 classes of objects related to the fight against the Islamic State group in Iraq and Syria.

Colonel Drew Cukor has previously said, “There is no 'black box' that delivers the AI system the government needs, at least not now. The only way to do that is with commercial partners alongside us."

Reports also revealed that Google is not the only U.S. firm involved in the project as chip-maker Nvidia too has previously blogged about Project Maven.